System of electrical distribution.



No. 687,!40. Patented Nov. l9, I90I. A. n. EVEREST.

SYSTEM OF ELECTRICAL DISTRIBUTION. (A 'nmim filed May 31, 1901.

(No Model.)

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UNITED STATES PATENT OFFICE.

AUGUSTINE R. EVEREST, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEIV YORK.

SYSTEM OF ELECTRICAL DISTRIBUTION.

SPECIFICATION forming part of Letters Patent No. 687,140, dated November19, 1901.

Application filed May 31, 1901.

T aZZ whom it may concern:

Be it known that I, AUGUSTINE R. EVEREST, a subject of the King of GreatBritain, residing at Lynn, in the county of Essex and State ofMassachusetts, have invented certain new and useful Improvements inSystems of ElectricalDistribution, (Case No. 1,818,) of which thefollowing is a specification.

My present invention relates to systems of IO electrical distribution orother circuits designed to operate with alternating currents, andcomprises certain arrangements of apparatus in connection therewithwhereby the voltage of the system or circuits may be automaticallyregulated in response to variation of load.

The principle of the invention may be explained roughly by stating thatan electromotive force of substantially constant value is inserted bysuitable means in series with one of the conductors or mains of thesystem. As the load on the system changes, this electromotive force isthrough shifting of phase of current in the system caused to be broughtmore or less into conjunction or opposition to the electromotive forcesimpressed upon the system, thereby either adding itself to orsubtracting itself from this impressed voltage, and so securing theregulation desired.

The features of novelty involved in my invention I have particularly setforth in claims appended hereto.

For abetter understanding of the invention itself, its construction, andmode of operation reference is to be had to the following detaileddescription, taken in connection with the accompanying drawings, inwhich Figure 1 shows one embodiment of my invention; Fig. 2, a slightlymodified form;

Fig. 3, still another modified form, and Fig.

4 an explanatory diagram.

In Fig. 1 a main source of electromotive force is indicatedconventionally at l and may consist of any suitable alternating-cur- 4 5rent dynamo-electric machine or other device for producing alternatingcurrents. This source of current is shown as connected to a step-upcompensator 2, the main winding of which is indicated at. and theboosting or secondary winding at 4:. Transmission or distributing lines5 and 6 extend from the Serial No. 62,592. (No model.)

outside terminals of the compensator 2, as shown, and serve to conveypower to translating devices of any desired character-such, for example,as motors, lamps, or other enorgy-consuming devices. In series with oneof these mainsas, for example, the main 6-- I connect an inductance-coil7 of special construction, the parts of the same being proportioned sothat its core is saturated throughout the range of load on thedistribution system. The reactive or inductive electromotive force dueto this coil is therefore approximately the same whatever be the amountof current flowing through its windings. Shunted across the mains orconductors 5 G 'is another inductance-coil 8, this coil beingproportioned, however, so that its core re mains unsaturated duringnormal operation. If there be no load on the mains 5 6, due to theconnection thereto of translating devices, then it will be evident thatthe only current flowing through the inductance-coil 7 will be thatsupplied by the generator to the inductance-coil 8 in shunt across themains. Since the inductance-coil 8 is highly inductive, the currentflowing through the inductance-coil 7 will consequently lag nearlyninety degrees behind the electromotive force impressed upon the mainsby the compensator 2. Since the reactive electromotive force due to theinductance-coil 7 lags ninety degrees behind the current flowing throughthe winding of this coil, it will therefore be evident that thisreactive electromotive force will by the shifting of phase of thecurrent due to the shunt inductance-coil 8 be brought nearly into exactopposition to the impressed electromotive force of the compensator 2.The parts are proportioned in a manner readily comprehended by oneskilled in the art, so that the drop across the terminals of theinductancecoil 7 is substantially equal to the voltage of the booster 4.These two voltages therefore practically cancel each other, so that atno load the voltage on the mains 5 0 is practically the same as thatbetween the terminals of the generator 1. This may perhaps be madeclearer by reference to Fig. 4, in which the horizontal line 9 10represents the total voltage of the compensator 2, that portion of theline between the points 10 and 11 represent ICO ing the voltage of thebooster 4, forming a part of the compensator. Since, as has been beforeexplained, the current through the inductance-coil 7 is at no loadnearly ninety degrees in phase behind the voltage 9 10 and since thereactive eleetromotive force of the inductance-coil 7 is lagged ninetydegrees further, it will be seen that this reactive voltage is by thisaction shifted nearly one hundred and eighty degrees or into a positionindicated by the line 12, drawn to represent the voltage across theterminals of the inductance-coil 7. The voltage on the mains 5 and 6will obviously be the 'resultant of the voltage represented by the line9 10 and that by the line 12, or, in other words, by the third side 13of the triangle, of which the lines 9 10 and the line 12 constitute theother two sides. When the load on the mains 5 6 increases, the laggingcurrent due to the shunt inductance-coil 8 forms a smaller and smallerproportion of the total load, d ue to which fact the lag of current inthe mains 5 6 gradually decreases as full load is approached until whenfull load is reached the angle of lag of the total current is very muchless than at no load. The effect of increasing load is therefore todecrease the angle of lag of the current, and therefore to shiftcorrespondingly the phase of the reactive eleetromotive force of theseries inductance coil 7, this electromotive force by the operationmentioned being moved from a position in practical opposition to theimpressed eleetromotive force through successive stages until it isbrought into a position closely approaching an angle of ninety degreesto the impressed eleetromotive force. This is illustrated in Fig. 4, inwhich 12' and 12 represent two succeeding angular positions of thereactive eleetromotive force of the inductance-coil 7. At 12", which maybe considered as corresponding to a position representing full load, thelag of current in the mains 5 6 is practically nothing, so that theeleetromotive force 12 is nearly at right angles to the impressedeleetromotive force represented by the line 9 10. The resultanteleetromotive force on the mains 5 6 is, as will be evident, shown bythe line 14, the length of which will from inspection be seen to beconsiderably greater than that between the points 9 11. In other words,the impressed voltage on the mains 5 6 rises with the load, as isnecessary in such cases.

The line 12 represents an intermediate position between no load and fullload, and the resultant 15 represents the corresponding vol tageimpressed on the mains 5 6, which, as will be seen, is somewhat greaterthan at low load and less than at full load.

In the description of Fig. 1, it is assumed that the generator 1 isadjusted so that its voltage is equal practically to the no-load voltageon the mains 5 6, the increased voltage at full and intermediate loadsbeing obtained through the instrumental ity of the booster 4. If,however, the main generator be worked normally at a voltagecorresponding to full load, then the use of a booster becomesunnecessary, and the arrangement of circuits will be as indicated inFig. 2. In this figure the inductance-coils 7 and 8 are the same as inFig. 1, the voltage on the mains 5 6 being in this instance equal to theresultant electromotive force of the generator 1 and the inductance-coil7, these eleetromotive forces combining in a manner already set forth inconnection with Fig. 4, and therefore requiring no further description.

It will be seen that if the main current as the load comes on could bemade to pass through successive stages of gradually-decreasing lag andthen become actually leading with respect to the eleetromotive force thevoltage of the inductance-coil 7, which when the current is lagging isalways to a greater or less extent in opposition to the impressedeleetromotive force, would with leading current be actually added to theimpressed electromotive force, thus securing an additional boostingeifect due to phase advancement of the main current. This result may besecured in a variety of ways, one instance of which is indicated in Fig.3. This figure corresponds in all respects with Fig. 1, with theexception that a condenser 16 is shunted across the outer terminals,respectively, of the booster 4 and the inductance-coil 7. By referenceto Fig. 4 it will be seen that at no load practically no voltage existsacross the terminals of the condenser 16, while withgradually-increasing load the voltage across the condenser increasescorrespondingly, this voltage being indicated by the successive dottedlines 17, 18, 19, and 20. As the load increases the condenser 16 willsupply a larger and larger leading current, which passing around throughthe inductance-coil 7 reduces the lag of current therein and at fullload may be caused to produce an actual leading of this current withrespect to the impressed electromotive force of the compensator 2. Theeleetromotive force across the terminals of the inductance-coil 7 maytherefore be shifted into some such position as represented at 12 inFig. 4, thereby producing a voltage across the mains 5 6 actuallygreater than the maximum voltage across the outside terminals of thecompensator 2. In Fig. 4 the line 21 represents this voltage and, aswill be seen, is longer than the line 9 10, representing the voltage ofthe compensator.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent of the United States, is-- 1. The combinationof conductors, means for impressing thereon a substantially constantelectromotive force, means for combining therewith a substantiallyconstant regulating electromoti ve force, and means responsive to theload for shifting the phase of the last-mentioned eleetromotive forcewith re .gpeet' to the first= mentioned electrom otivo orce.

2. The combination of conductors, means for impressing thereon asubstantially constant electromotive force, means connected in serieswith one of said conductors for producin g a substantially constantelectromotive force, and automatic means for-shifting the phase of, thelast-mentioned electromotive force with respect to the first-mentionedelectromotive force so that at small loads it will be in partialopposition thereto and at greater loads in partial conjunctiontherewith.

8. The combination of distributing or transmitting conductors, means forimpressing thereon an electromotive force, an inductance-coil in serieswith one of said conductors, and another inductance-coil in shunt acrosssaid conductors.

4. The combination of a source of electromotive force of constantpotential, distributing or transmitting conductors connecting thereto,an inductance-coil in series with one of said conductors, and anotherinductancecoil in shunt across said conductors.

5. The combination of a step-up compensator, mains extending from theterminals thereof, an inductance-coil in series with one of said mains,and another inductance-coil in shunt to said mains.

6. The combination of a step-up compensator, mains extending therefrom,an inductance-coil having a normally-saturated core in series with oneof said mains, and another inductance-coil in shunt to said mains.

7. The combination of a Winding constituting a source of electromotiveforce, mains extending therefrom, an inductance-coil in series with oneof said mains, another inductance-coil in shunt to said mains, and acondenser connected between an intermediate point in said winding andone terminal of the series-connected inductance-coil.

In Witness whereof I have hereunto set my hand this th day of May, 1901.

AUGUSTINE R. EVEREST.

